THE USHER has some announcements to make first. Switch off your mobile phones. Go to the loo now, as it's two hours, without an interval. Don't leave your seat - as someone did the night before - or you'll bump into an actor.

Then he leads us from the BAC cafe into a "space" where we take seats that circle round a steel frame with a coiled rope hanging down. The doors close. The blue light fades. The exit sign goes out. It's pitch black. All I can hear is the squeak of a neighbour's leather jacket as he shifts in his seat. This is the press night for Sophocles' Oedipus Tyrranos: the centrepiece of the BAC current season, "Playing in the Dark". None of us will ever be able to say we saw it. Only that we heard it.

The "dark" season is another piece of clever programming by BAC director Tom Morris. But is it anything more than going to the theatre and finding yourself listening to the radio? And, to start with, it is a bit like The Archers: we get scratching noises, like the tapping of chalk on a blackboard. Rats, you think. The plague must be visiting Thebes. After a long pause, we hear Oedipus shifting through the darkness to deliver his first line. We know where he is when he bumps into a chair.

If you're going to turn the lights out on a classic, then Oedipus is a smart choice. Oedipus spends the play, metaphorically, in the dark. Then, when he finds out about his mum, his dad and his missus, he blinds himself. The knowledge makes his darkness even greater.

Turn out the lights and everything depends on the quality of the voices and the sound effects. Here, Tom Morris's illuminating production falters. The company's moaning, whispering and shuffling need stronger definition. Nor do you to want to spend that long in the dark: at two hours - this is a leisurely Oedipus. Tam Dean Burn's Oedipus is an expressive figure who labours the lines with heartfelt emotion. He doesn't bring the brisk, searching intelligence necessary to drive this play forward and make it - at one level, at least - a detective thriller.

The production scores best when surprising visual remarks leap out of the dark - Dean Burn telling the Shepherd (Neil Macleod) to lift up his head; or in the set-piece descriptions, most notably when the messenger (Jim Bywater) relates how Jocasta (Denise Evans) killed herself and how Oedipus found her hanged and then stabbed his eyeballs with a golden pin. Sitting through these moments, written for audiences who listened far more intently than we do, the dark is light enough.

A woman sits on a train and wonders whether to take a book out of her bag. What makes her hesitate is the sight of the man sitting opposite. He wrote it. As the premise for a play it's modest. But then Yasmina Reza, the author of The Unexpected Man, which transferred last week into the West End, created Art out of a dispute over a blank canvas.

In The Unexpected Man these two - superbly played by Michael Gambon and Eileen Atkins - think about themselves, shoot glances, and think about each other. At the end, they talk. He is an embittered novelist on his way to meet his prospective son-in-law. She is a widow, has just lost a close friend, and reads his novels with a passion.

In Mark Thompson's abstract, fragmented designs, chairs are dotted along a railway track that traverses a sheet of Perspex glass raised above a bed of shingle. Gambon and Atkins cross and uncross their legs, get up, walk round, return. They are physical opposites. If they were puddings, he would be jelly, she would be a brandy snap. But both have a charge that comes from loneliness and unease. Gambon builds round contrasts: lightness and weight; bitterness and charm; alertness and fatigue. Atkins is crisp, idealistic and withering.

We see in The Unexpected Man what we saw in Art. Reza knows how formal constraints create energy on stage. She is sharp on the dissatisfactions of cultured bourgeois life. Her characters isolate moments and pick away at them. She writes - intriguingly - about the dramas going on inside people's minds: the conversations that never take place. The Unexpected Man draws its structural vigour from anticipation. As the train travels from Paris to Frankfurt, these two move closer. But the encounter could be brief.

The literary ironies are elegant: Atkins has one of the major relationships of her life with someone she has never met. He feels old, yet his books exist in a perpetual present tense. Liking the books doesn't mean liking the man. Atkins doesn't think even the characters in Gambon's books would enjoy the books. Director Matthew Warchus shapes these enticing reveries with the same depth and polish he brought to Art. The excellent translation, again, is by Christopher Hampton.

The Basset Table opens with characters playing cards at four in the morning. The manservants are slumped around waiting for their employers to finish playing Bassett. It all looks good rakish fun, if you're not a manservant. Susanna Centlivre's lively restoration comedy has husbands who can't control their wives' desires for gambling or for men. Just in case 1705 sounds an awfully long time ago, director Polly Irvin treats us to blasts of rock, strobe lighting and modern footwear.

It's a shame. Half the show is good: bosoms heave, eyes flash and wrists hang suspended in the air. As Lady Reveller, Harriet Thorpe has exactly the right poise: a regal seductiveness and acidic tone. "Who could endure these men," she comments, "did they not lose their money." But some of the cast fatally send up their characters. The young men give us mannerisms when we want manners. Irvin's takes Centlivre's play, slaps on the rouge, powders its nose and sticks ringlets in its hair. Never mind the scene- changes: you want to find the rock'n'roll in the performances.

'Oedipus': BAC, SW11 (0171 223 2223), to Sun 28 Jun. 'The Unexpected Man': Duchess, WC2 (0171 494 5075). 'The Basset Table': Tricycle, NW6 (0171 328 1000), to 11 Jul.